The premature detonation of such explosive devices as flares, bombs, missiles, or mortars during handling, shipping, or in storage creates a highly dangerous condition. Various safety and arming devices have been proposed in the prior art for preventing accidental arming and premature detonation of munitions. A safety and arming device is now a required element of a munition to ensure that the munition is not armed and detonated until the desired time. The safety and arming device is part of a munition's fuze and prevents arming of the fuze until certain conditions are met. Many safety and arming devices require two conditions or occurrences for operation and initiation of the fuze. The first condition utilized is typically setback acceleration which is associated with the launching of the munition. Setback acceleration of the munition is a convenient condition to measure. The second condition can be based on a number of different parameters such as barrel escape velocity, timing, counting turns or rotations of the munition, etc.
One early safety and arming device is the percussion fuze. A percussion fuze is normally held inoperative by a safety device which is released by setback forces developed upon launching of a projectile. Such a fuze is shown in U.S. Pat. No. 1,652,635.
Another proposed safety and arming device includes a fuze wherein movement of a setback slide mechanism pivots a lever. The movement of the lever activates a timing mechanism. The timing mechanism releases a detonator carrier which is moved into an armed position. One such device is shown in U.S. Pat. No. 2,863,393.
Still another type of fuze device has been proposed in which a slide mechanism responds to setback forces developed during sustained acceleration of a projectile to arm the fuze. A typical device of this type is disclosed in U.S. Pat. No. 2,595,757, and more recently in U.S. Pat. Nos. 4,284,862 and 4,815,381.
Other examples of prior devices that use the setback acceleration condition to arm a fuze include zig-zag gravity weights, gravity weight driven escapements, successive falling leaves, and various combinations of these devices.
However, many of these devices suffer from several drawbacks. For example, many require a great number of parts, many require close tolerances between these parts, and many have limited accuracy and reliability. More specifically, in some prior safety and arming devices, a latch must move in order to catch a setback lock before rebounding. This creates a “race” wherein the latch has to catch the setback lock before rebounding in order for the device to work. Devices utilizing these designs are typically of lower reliability than desired and can lead to a greater risk of unintended arming. Further, these prior arming devices, because of the great number of independent parts required for their operation, typically require more space than is sometimes desired or available.
While all these various safety and arming mechanisms are suitable for their intended purposes, there is room in the art for an improved safety and arming mechanism that is easy to assemble, less costly to manufacture, compact in size and, most importantly, extremely reliable.
Accordingly, it is an object of the present invention to provide the art with an improved safety and arming mechanism with reliable interaction of components while simultaneously reducing the number of component parts required for operation of the mechanism.